embryology

Question 1

what weeks are the embryonic period

Answer 1

3-8

Question 2

what weeks are the foetal period

Answer 2

9-40

Question 3

what weeks are the first trimester

Answer 3

weeks 0-12

Question 4

what weeks are the second trimester

Answer 4

weeks 12-24

Question 5

what weeks are the third trimester

Answer 5

24- birth

Question 6

name the phases of embryogenesis

Answer 6

gametogenesis
fertilisation
cleavage
gastrulation
formation of body plan
organogenesis

Question 7

what takes place during gametogenesis

Answer 7

formation of haploid gametes

oogenesis
spermatogenesis

Question 8

how many pairs of chromosomes are in a gamete

Answer 8

23

Question 9

describe oogenesis

Answer 9

formation of the female gametes

starts at development and ends at menopause

weeks 28-30 of development oocytes begin meiosis but arrest in prophase until puberty

Question 10

when is reproductive lifespan of the female determined

Answer 10

during foetal life

Question 11

describe spermatogenesis

Answer 11

formation of the male gametes

takes place during puberty and continues throughout life

Question 12

how many sperm are produced each day

Answer 12

~65 million per gram of testicular tissue

decreases with age

Question 13

what is aneuploidy

Answer 13

abnormal number of chromosomes

Question 14

describe fertilisation

Answer 14

fusion of gametes to form a zygote

Question 15

define zygote

Answer 15

diploid single cell embryo

Question 16

where does fertilisation usually occur

Answer 16

ampulla

Question 17

what is polyspermy

Answer 17

when multiple sperm fertilise one egg

leads to a non-viable embryo

Question 18

describe cleavage

Answer 18

rapid mitotic cell division

cells decrease in size so no change in the size of the zygote

formation of morula (16+ cells) then blastocyst (~4 days after fertilisation)

cavity inside blastocyst - trochoblast will form placenta and epiblast will form embryo

Question 19

describe gastrulation

Answer 19

formation of the germ layers - takes place in week 3

ectoderm, mesoderm and endoderm form

body axis established

Question 20

what does the ectoderm go on to become

Answer 20

outer layer of the embryo

skin and nervous tissue

Question 21

what does the endoderm go on to become

Answer 21

inner layer of the embryo

GI and respiratory tracts

Question 22

what does the mesoderm go on to become

Answer 22

middle layer of the embryo

muscle and skeletal tissue

Question 23

what is embryonic folding

Answer 23

formation of the body plan

Question 24

what is organogenesis

Answer 24

formation of the organs and organ systems

basis of this is in place by the end of the embryonic period, continues to develop during the foetal period

Question 25

when does the foetus growing in length mainly occur

Answer 25

2nd trimester

Question 26

when does increase in foetal weight mainly occur

Answer 26

3rd trimester

Question 27

what occurs during the foetal period

Answer 27

tissues mature and become functional
overt sexual differentiation
bone laid down
connections made in CNS

2nd trimester - grow in length
3rd trimester - weight gain

Question 28

what is the term used instead of superior when referring to an embryo/ foetus

Answer 28

cranial

Question 29

what is the term used instead of inferior when referring to an embryo/ foetus

Answer 29

caudal

Question 30

what is the term used instead of anterior when referring to an embryo/ foetus

Answer 30

ventral

Question 31

what is the term used instead of posterior when referring to an embryo/ foetus

Answer 31

dorsal

Question 32

what factors control development of an embryo/ foetus

Answer 32

gene expression
epigenetic factors - preferential expression of genetic factors in relation to the environment